The purpose of this study is to explore a new way to examine the function of the muscles using a technique called high-resolution manometry. The study will enroll 30 adults with OSA, all of whom will use the myofunctional therapy (MFT) devices for 3 months. High-resolution manometry will be used to measure the amount of pressure generated by the muscles of the throat when drinking water or breathing air, both with and without the MFT devices, and before and after the MFT intervention. If successful, this method can help us understand why sleep improves after MFT.

Inclusion Criteria:

• Adults aged 18-65
• New diagnosis of OSA (AHI ≥ 5) or failure of first-line OSA treatment
• Willingness to forego first-line OSA treatment or stop current OSA treatment for 3 months

Exclusion Criteria:

• Medical comorbidities that require restricting fluid intake (e.g., dysphagia, renal disease, liver disease, hyponatremia)
• Severe nasal obstruction
• Severe ankyloglossia
• Craniofacial abnormality
• Severe pulmonary disease
• Severe post-traumatic stress disorder (PCL-5 > 33)
• Very severe insomnia (ISI > 22)
• Body mass index (BMI) ≥30 kg/m2.
• History of TBI
• Known oropharyngeal or esophageal dysphagia
• Pregnancy
• Allergy to topical anesthetic
• Inability to fast for 6 hours
• Recent facial trauma
• Recent nasal, pharyngeal, laryngeal, or esophageal surgery
• Known nasal, pharyngeal or esophageal obstruction
• Current upper respiratory infection
• Insufficient internet/computer access to participate in remote study visit
• Severe excessive daytime sleepiness (risk of motor vehicle accidents)
• Heart failure, recent stroke, heart attack, etc.
• Nasal Obstruction Symptom Evaluation (NOSE) Scale >15